Machine for the manufacture of a fibrous plasterboard web

ABSTRACT

A machine for the manufacture of a fibrous web includes a back liner former, a top liner former and at least one middle layer former. The back liner former is configured for producing a back liner, comprised of a fibrous web, with one side of the back liner having a higher fines content. The top liner former is configured for producing a top liner, comprised of a fibrous web, with one side of the top liner having a higher fines content. The middle layer formers, being configured for producing at least one middle layer, comprised of a fibrous web, with one side of the middle layer having a higher fines content, the other side of the middle layer having a lower fines content. Each middle layer former and the top former having couch rolls that define an associated couching zone; wherein the back liner former and each middle layer former are configured such that the side of the higher fines content of the back liner contacts the lower fines content side of the middle layer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a machine designed for the manufacture of a fibrous web, in particular a paper or carton web and preferably a plasterboard web.

[0003] 2. Description of the Related Art

[0004] Several different former combinations have been proposed for the manufacturing of plasterboard:

[0005] In a machine design including two gap formers, drainage in both gap formers is affected firstly on the top wire side and subsequently on the bottom wire side, resulting in a higher fines content on the bottom wire side. A back liner top side, with a lower fines content, is couched together with the top liner bottom side, which has a higher fines content.

[0006] In a machine design including several cylinder mold formers, a concentration of fines is produced on the cylinder wire side. The top sides, which have a low fines content, are couched together with the wire sides which have a high fines content.

[0007] In a machine design having two machine wire webs for the top liner and the back liner, respectively, together with a so-called BelLiner gap former for middle layers, a concentration of fines on the top side is produced with the machine wire webs, and a concentration of fines on the bottom wire side is produced with the BelLiner gap former. The sides of high fines content of the top liner and a first middle layer are couched together with the sides of low fines content of the first middle layer with a second middle layer and the back liner.

[0008] In a machine design including a combination of several machine wire webs, a concentration of fines is produced on the top side during the machine wire drainage process. The top liner and the middle layers are couched together with their top sides of high fines content and the bottom facing wire sides of low fines content. The middle layer and the back liner are couched together with their top sides of high fines content facing each other.

[0009] In a machine design for the packaging industry having two gap formers, a so-called “DuoFormer Base” (PB 10656) and a so-called “DuoFormer Top” (PB 10449) with the same web running direction are provided in the sheet-forming process. In this case, the top wire side of low fines content is couched together with the bottom wire side of high fines content.

[0010] A disadvantage of the above machines lies in the fact that purposeful separation of the back liner and middle layer is not possible.

SUMMARY OF THE INVENTION

[0011] The present invention provides a machine for the manufacture of a fibrous web, particularly a plasterboard web, which allows a purposeful separation of the back liner and middle layer.

[0012] The present invention also provides a method of feeding the back liner and middle layer which are to be couched together into the relevant couching zone in such a way that the back liner side, with a higher fines content, comes into contact with the middle layer side, with a lower fines content.

[0013] This development results in reduced adhesion between the middle layer and the back liner, allowing the purposeful separation of the back liner without causing the destruction of the top liner and the middle layer. A further advantage is achieved with regard to a possible alteration of the properties of the paper in terms of porosity, roughness, penetrative and printing characteristics.

[0014] For practical purposes, a Fourdrinier former is provided to produce the back liner, in which the sheet-forming process for the back liner is effected with a higher fines content on the top side facing away from the Fourdrinier wire web.

[0015] Ideally, the middle layer is produced by a gap former containing a forming element in which the sheet-forming process for the middle layer is effected with a higher fines content on the side of the forming element. The forming element used is preferably a forming roll.

[0016] In a preferred embodiment the jet direction of the headbox assigned to the middle layer former is set against the jet direction of the headbox assigned to the back liner former.

[0017] In an expedient and practical embodiment of the machine in accordance with this invention, the middle layer is reversed by a couch roll provided in the area of the respective couching zone.

[0018] By preference, the back liner top side with a higher fines content is couched together with the top wire side of the middle layer with a lower fines content.

[0019] It may be advantageous for the machine to be provided with a Fourdrinier former to produce the top liner, in which the sheet-forming process for the top liner is effected with a higher fines content on the top side facing away from the Fourdrinier wire web.

[0020] In an expedient and practical embodiment of the machine, the top liner which is to be couched with the middle layer is reversed on a couch roll provided in the area of the respective couching zone.

[0021] It may also be advantageous for the top side of the top liner with a higher fines content to be couched together with the bottom wire side of the middle layer with a higher fines content.

[0022] The gap former may be provided with either a single-layer or a multi-layer headbox.

[0023] Where required, constant pressure drainage elements can be provided for web drainage purposes. These may be used in combination with any of the formers. An example describing how they may be implemented can be found in document DE 197 33 316 A1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein:

[0025]FIG. 1 is a schematic illustration of a machine for the manufacture of a fibrous plasterboard web.

[0026] The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring now to the drawings, and more particularly to FIG. 1, there is shown a schematic drawing of a machine 10 for the manufacture of a fibrous web 12, in particular a plasterboard web, including back liner R, top liner D and middle layer E positioned therebetween.

[0028] Back liner R is produced by Fourdrinier former 14, middle layer E is produced by gap former 16 and top liner D is produced by Fourdrinier former 18. In each case, sheet-forming is effected in such a way as to produce a higher fines content on one side of the respective layer than on the opposite side.

[0029] Back liner R and middle layer E, which are to be couched together, are fed into respective couching zone 20 in such a way that the side of back liner R, which has a higher fines content, comes into contact with the side of middle layer E which has a lower fines content.

[0030] Sheet-forming of back liner R in Fourdrinier former 14 is effected with a higher fines content on the top side facing away from Fourdrinier wire web 22.

[0031] Gap former 16 containing forming element 24 for the sheet-forming of middle layer E which is effected with a higher fines content on the forming element side. Forming element 24 is preferably a forming roll.

[0032] The jet direction of headbox 26 assigned to gap former 16 is generally set against the jet direction of headbox 28 assigned to Fourdrinier former 14.

[0033] Middle layer E is reversed on couch roll 30 in couching zone 20.

[0034] In the above case, the top side, with a higher fines content, of back liner R is couched together with the top wire side, with a lower fines content, of middle layer E.

[0035] Forming shoe 34 can be provided within the loop of top wire 32 in gap former 16.

[0036] Top wire 32 is guided over breast roll 38 in the area of fiber mixture wire gap 36. Headbox 26, loaded with fiber pulp slurry, feeds the fiber pulp slurry into fiber mixture wire gap 36.

[0037] Sheet-forming of top liner D in Fourdrinier former 18 is effected with higher fines content on the top side facing away from Fourdrinier wire web 22.

[0038] Top liner D, which is to be couched with middle layer E, is reversed on couch roll 42 in couching zone 40.

[0039] In the above case, the top side, with higher fines content, of top liner D is thus couched together with the bottom wire side, with higher fines content, of middle layer E.

[0040] The resulting distribution of fines is depicted in symbol form in the left-hand section of FIG. 1.

[0041] Gap former 16 may be provided with a single-layer or multi-layer headbox 26.

[0042] The jet direction of headbox 44 assigned to Fourdrinier former 18 is generally set against the running direction of Fourdrinier wire web 22, through which layers R, E (which are already couched together) are fed into second couching zone 40.

[0043] Where required, constant pressure drainage elements 46 can be provided for purposes of web drainage. These may be used in combination with any of the formers.

[0044] While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. 

What is claimed is:
 1. A machine for the manufacture of a fibrous web, comprising: a back liner former configured for producing a back liner comprised of a fibrous web, the back liner having a higher fines side with a higher fines content; a top liner former configured for producing a top liner comprised of a fibrous web, the top liner having a higher fines side with a higher fines content; and at least one middle layer former configured for producing at least one middle layer comprised of a fibrous web, the middle layer having a higher fines side with a higher fines content, and a lower fines side with a lower fines content, each said middle layer former and said top former having a couch roll defining a couching zone associated therewith, wherein said back liner former and each said middle layer former are configured such that the higher fines side of the back liner contacts the lower fines side of the middle layer.
 2. The machine of claim 1, wherein said back liner former is a Fourdrinier former having a first machine wire web; said first machine wire web being configured to convey a fibrous web, with the higher fines side of the back liner facing away from said first machine wire web.
 3. The machine of claim 1, wherein said at least one middle layer former is a gap former having a forming roll, said gap former being configured to produce the middle layer in a manner such that the higher fines side thereof faces said forming roll.
 4. The machine of claim 1, further comprising a first headbox and a second headbox, said first headbox being associated with said middle layer former and said second headbox being associated with said back liner former wherein the jet direction of said first headbox is generally opposite the jet direction of said second headbox.
 5. The machine of claim 1, wherein said couch roll of each said middle layer former is configured to redirect the flow of the middle layer in said couching zone.
 6. The machine of claim 1, wherein said back liner former and one of said middle layer formers are configured such that the higher fines side of the back liner is couched together with the lower fines side of the middle layer.
 7. The machine of claim 1, wherein said top liner former is a Fourdrinier former having a second machine wire web, said second machine wire web being configured to produce the top liner with the higher fines side of the top liner facing away from said second machine wire web.
 8. The machine of claim 1, wherein said couch roll of said top liner former is configured to redirect the flow of the top liner in said couching zone.
 9. The machine of claim 1, wherein said machine is configured such that the higher fines side of the top liner is couched together with the higher fines side of the middle layer.
 10. The machine of claim 1, wherein at least one of said middle layer formers includes a single layer headbox.
 11. The machine of claim 1, wherein at least one of said middle layer formers includes a multi-layer headbox.
 12. The machine of claim 1, wherein at least one constant pressure drainage element is included in association with at least one of said back liner former, at least one of said at least one middle layer former and said top liner former. 